A. Field of Invention
This invention relates to the art of ball joints and more specifically to methods and apparatuses related to a friction controlled ball joint.
B. Description of the Related Art
It is well known to use ball joints in widely varied mechanical applications including automotive chassis systems, aircraft landing gear systems, and agricultural machinery. The fundamental function of a ball joint is to connect two mechanical parts together while allowing relative rotational movement of the parts. Friction exists in ball joints due to the inherent mechanical interference. Excessive friction is a disadvantage in that it negatively influences the dynamic behavior of the mechanical system. Moreover, mechanical friction of known ball joints degrades with time and, often of more concern, causes a significant variation in the dynamics of the system. Sometimes, however, friction in ball joints can be a positive characteristic helpful for damping the relative motion of the parts and/or adding resistance for the relative motion.
FIG. 7 illustrates a conventional ball joint assembly 200. The ball joint assembly 200 includes a housing 202 having a seat 204 that receives a ball stud 206. The ball stud 206 includes a ball 208 and a shank 210. A plug 212 holds the seat 204 within the housing 202 and a clip 214 holds a dust boot 216 to the housing 202. Friction occurs between an outer surface 218 of the ball 208 and an inner surface 220 of the seat 204. This friction is fixed and uncontrollable after the ball joint assembly 200 has been put together.
What is needed is a ball joint assembly that permits the friction between the ball and the seat to be controlled.